1. Field of the Invention
The present invention relates generally to pipeline-pig launchers and relates specifically to a launcher used at a subsea location and having a magazine holding a plurality of pigs for launch.
2. Description of the Prior Art
Oil and gas flowing through a production pipeline can deposit paraffin and other substances on the inner wall of the pipeline. To prevent blockage, producers send pipeline pigs through the pipeline to scrape the walls and remove the deposits.
Several pig launchers having storage and launching capabilities are found in the prior art. The device disclosed in U.S. Pat. No. 3,396,789 has a rotatable tool holder that is journaled within a case. The tool holder has a plurality of tubes that can be aligned with the flowline. There is no provision for releasing individual tools from each tube, and if more than one tool is in a given tube, they will all be released when aligned with the flowline.
The pig launcher of U.S. Pat. No. 5,884,656 includes a single tube containing multiple pigs and has the ability to launch only one pig at a time.
A stabbing configuration and magazine are found in the pig launcher disclosed in U.S. Pat. No. 6,022,421. The pig launcher is landed on a frame having a connector for introducing the pigs into a production pipeline. The launcher has a single tube magazine and can launch single pigs.
A pig launcher is provided for use in a subsea location. The launcher has a frame for landing on the sea floor and a magazine for storing and controllably releasing a set of pigs. A drive assembly sequentially releases the pigs, and a set of interconnects releasably connects the pig launcher to a production flowline. An umbilical stab releasably received in a receptacle in the frame is used to control the operation of the drive assembly and receives power from . An umbilical line runs from the stab to a surface platform to supply a source of power for operational control.